During the fabrication process, various steps can cause defects in the metallization features of a device. For example, during a chemical mechanical polishing (CMP) process, corrosion of a metal fill may occur. Specifically, the metal fill can thermodynamically oxidize and will not self-passivate, so that oxidation continues, thereby causing corrosion. Examples of types of corrosion which may occur include pitting and dishing, amongst other examples.
During an annealing and/or etching process, out-diffusion of the metal fill may also occur, resulting in protrusions of the metal fill. During a deposition process, such as the deposition of a layer over the metal fill, surface migration of the metal fill may occur, resulting in the metal fill diffusing into the surrounding dielectric material and in time-dependent dielectric breakdown (TDDB). Additionally, electromigration of the metal fill may occur, resulting in voiding of the interconnect lines.